<?php

class Persion {
    public $name = 'lisi';
    public $self = null;
    public static $age = 22;
    public function intro(){
        echo 'my name is: '.$this->name;
        echo 'my age is: '.self::$age;
        $this->self = new self();
    }
    public static function getAge(){
        return self::$age;
    }
    public function getAge1(){
        echo $this->age,'<br/>';
    }
}


$lisi = new Persion();
$lisi->intro();